When you are targeting a crowded market like IP telephony in the cloud, it helps to differentiate your service. With that in mind, RingCentral, a company backed by venture capital from Sequoia, Khosla, Cisco and others, has added a fax feature that integrates directly with several of the most popular cloud data storage services.
RingCentral CloudFax offers one-click faxing from Box, Dropbox or Google Docs (ala the screenshot below).
The idea is to make the fax process simpler, especially for small companies that still have to send out large volumes. The service allows the sender to send documents from multiple locations and to schedule them for delivery at a later time.
The fax service is free, but only if you are customer of the RingCentral cloud business phone services.